A South African man with Parkinson’s disease, a degenerative disorder that often leaves its sufferers immobile, walks his symptoms into submission. A Broadway singer, silenced for 30 years by multiple sclerosis, recovers his voice. And in California, a psychiatrist and pain specialist rids himself of 13 years of chronic pain within a year, without drugs or surgery, through his brain’s own efforts. Those individuals, and thousands like them, achieved those results, writes Norman Doidge, a Toronto psychiatrist and author of The Brain’s Way of Healing, precisely because the human brain is a generalist par excellence. The prevailing 20th-century view was that it was too specialized for its own good—a fixed machine made up of discrete parts that can break down, never to function again. That concept no longer stands up to scrutiny.

The brain is actually a supple, malleable organ, as ready to unlearn as it is to learn, capable of transforming vicious circles into virtuous circles, of resetting and repairing its internal communications. Far more than once dreamed possible, the brain can—if not always cure—heal itself.

Doidge wrote about the brain’s remarkable ability to recalibrate itself—what doctors call neuroplasticity—in his 2007 bestseller The Brain That Changes Itself. His new book recounts an astounding array of radical improvements in brain problems long thought irreversible. There are newly effective therapies, leading to improvement in, and sometimes even complete cures, for conditions ranging from stroke to traumatic brain injuries, learning disorders and missing brain parts. Even Parkinson’s and MS symptoms can be improved in new ways. “Like Marshall McLuhan said, the future is already here,” says Doidge in an interview. “The early neuroplasticians had to battle to get their findings accepted but now the field is not remotely controversial. I’m no longer talking about ‘promising’ developments down the road, but therapies that are here now. Patients and their caregivers just have to know who is doing things they thought impossible.”